Circuit Design of Infra-Red / RTC add-on board for Raspberry Pi GPIO

Raspberry Pi Real-Time Clock Infra-Red Sender / Receiver PCB Design The purpose of this project is to design and prototype a small PCB circuit which connects directly to the GPIO pins of a Raspberry Pi Model 3 B to provide 3 x IR transmission outputs, and 1 x IR receive input, together with a real time clock module using a PCF2127 chip and CR1220 battery backup. 3.5mm jack sockets are to be used for the connectors to the emitters and receivers. The PCB board itself will just have solder holes to connect wires leading to the jack sockets - the jack sockets themselves are not required on the board. The board should ‘plug in’ directly to the Raspberry Pi GPIO pins with a suitable connector on the board. No software development is required. Real-Time Clock The real time clock component should use a PCF2127 chip connected to the GND, 3.3V, SDA and SCL pins of the Pi GPIO pins - example circuit to be supplied. Infra-Red Emission: A single GPIO pin is being used for the infra-red output - but each of the 3 x output connectors can optionally be isolated via a relay, so that certain output connectors can be isolated when sending infra-red signals. In other words, the infra-red signal transmitted will go through 1, 2 or all 3 of the output connectors, depending on the state of the relays. The relays themselves will be driven by 3 separate GPIO pins on the Pi. A suitable relay / switching mechanism should be chosen, possible with extra circuitry to cope with the output voltage of the GPIO pins. The default should be that with the GPIO pin low, the IR signal comes out of the output - as most of the time the same IR signal is required on all outputs. Data sheets & samples of the IR transmitters to be supplied Infra-Red Receive A single Infra-Red receive connection to a GPIO pin is required. Data sheets & samples of the receiver to be supplied. Design Concerns 1. Power consumption of the IR emitters / receiver, particularly when using all 3 IR outputs at the same time 2. When IR emitters or receivers are connected or disconnected via the jack sockets, there is a brief short circuit between power & ground, resulting in a reboot of the Raspberry Pi which is not desirable. Deliverables: 1 x Circuit Diagram in pdf format 1 x PCB layout diagram in pdf format and standard format for manufacture 1 x working prototype board We will provide a Raspberry Pi with working prototyped circuit for 1 IR emitter & receiver, and also the IR emitters / receivers for testing, along with a working software script which tests the input & outputs & a sample RTC circuit.